I don't understand some aspects of the ND3ST measurements. The distortion profile is very flat and low compared to every other compression driver I have seen (perhaps the level only been 104dB/1m ?*) and the waterfall plot has a lot of activity <5khz and no sign of breakup in the upper octave which again is weird. The unusual aspects of the driver seem to be the 4 slot phase plug, attachment of the voice coil and Nomex former. Anyone able to explain whats going on?
*This is actually the same level as the Eminance was tested at
I think it was probably measured at 94db by accident. The distortion profile looks similar other compression drivers measured at that level.
Can't get around physics. Second harmonic should be higher.
Can't get around physics. Second harmonic should be higher.
I talked with Vance about it, becouse I also was surprised with it. He confirmed, that the measurments were performed at the same conditions as for other compression drivers, so there is no mistake.
CSD/waterfall looks rather poor though.
CSD/waterfall looks rather poor though.
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Interesting...the larger 4015 series don't display similar levels of low distortion. I wonder how they achieved those levels.
The diaphragm has an integrated surround that looks like it's a "single ply" where the diaphragm itself is "double ply": basically forming two foils together for the "dome" and using only one foil for the surround.
In any event, the surround is very lightweight and does a poor job of suppressing "hash" - (perversely) it should sound great as a result, with lots of low-level detail, like a typical electrostat.
The real problem with it is the hard non-linear rise (just below 1 kHz) because of that type of surround. 18 Sound engineers "combat" this to an extent with a dome profile and phase-plug that allow the response to extend *fairly well at its highest freq.. In effect then, this is purely a treble driver despite the fact that it's a 1.4" exit driver. My guess is that it should have a high-pass crossover between 1.6 and 3 kHz (depending on slope) to get the best from it.
*though unless you couple it to a diffraction slot horn, you'll end up with some treble loss off-axis relative to the average at that last upper-freq. half-octave.
Note: this sort of excellent engineering is why I said earlier I wish that 18 Sound would make a compression driver with textreme.. (..that and Eminence's compression driver engineering is "bush-league" by comparison.)
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I'm holding out for a 4 inch VC diaphragm of TExtreme material.
They seam to be the better application for it as breakup of aluminium and Titanium variants start around 6khz, which is just about in the sensitive range for hearing. TrueExtent diaphragms are silly prices these days (1300 euro each!) in 4 inch variety. Hopefully the light material will also be more efficient at the top end too, so I don't need so much EQ to get output at 16khz.
I will just need to get a driver to put it in that doesn't rise in distortion to much when pushed below 800hz and I'm golden!
They seam to be the better application for it as breakup of aluminium and Titanium variants start around 6khz, which is just about in the sensitive range for hearing. TrueExtent diaphragms are silly prices these days (1300 euro each!) in 4 inch variety. Hopefully the light material will also be more efficient at the top end too, so I don't need so much EQ to get output at 16khz.
I will just need to get a driver to put it in that doesn't rise in distortion to much when pushed below 800hz and I'm golden!
I guess that TExtreme would be similar to JBL Aquaplas. Better than bare titanium, but not as good as Be.
Truextent diaphragms measurements
Truextent diaphragms measurements
Just fitted my Aquaplas diaphragms this week. After nearly 100 measurements, I still have much work to do on the EQ.🙄
Its hard to swallow -30 db of EQ. Perhaps I need to investigate some passive components to get the hump from 300 to 20khz flat.
Smooth sound, but again, breakup at 12.5k is clearly there in the measurements. Short of that, they measure better than almost anything comparable.
didn't want to use boost and lose dynamic range too much. I also have foam in the horn so this makes it worse.
Not at all.
Textreme can be altered in shape and *damping far more than metal, and the surround can also be quite different (with varying levels of material integration with the diaphragm).
It will be interesting to see what other manufacturers do with the material and what sort of materials they will use with it. (..materials ex.: the foam at the core could change and have variable properties including spot damping. Also, the resin "binder" could have metal flakes, diamond flakes, carbon nanotubes, or graphene flakes.)
*for instance you can surface treat metal, but it's far more difficult to alter damping within the diaphragm itself.
One notable difference for the Eminence driver is its extended top-end. Sure, it's well below the average with this horn, but it doesn't just end with an abrupt resonance near 20 kHz.
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Kinda reminds me of the early 90s. All the speaker manufacturers started making drivers in various variations on plastic. Various formulations, various composites, profiles, etc.
After a while a lot of the same companies reverted back to coated paper because it worked better.
My other hobby is building bikes. I used to do a lot of work with carbon fiber. Eventually I reverted back to aluminum, fiberglass and even wood.
Basically carbon fiber is a neat material, but it's challenging to justify it's cost. If it's cost was equal to aluminum and fiberglass I'd probably use CF a lot more. I haven't made anything out of CF in at least three years, and I used to use it every week at first. Just got to the point where the expense couldn't justify the performance.
Off topic, but I had a student who built a bike out of bamboo for their final project. It was awesome and with reinforcement in the right places, road better than anything I have used before. We ended up spending many hours working on improving it by swapping parts out for different thicknesses and shapes. The trick ended up being to make a very strong triangle for the rear half, but curving the bottom bar so it had some 'whip'. With practice, you could use the whip to store energy and make the bike jump. The front was a little softer in the z axis, but very ridged in the X and Y, and torsion between the front and rear needed to be progressive rather than ridged.
That was the best project I've seen for understanding pliability of materials in real world uses. My god did he put a lot of hours in though.
On the TExtreme, if they are aiming at DIY market, they can afford to loose some efficiency to get a higher 1st resonance than OEMs. If they are after the pro market I can't see it being as good, but a sandwich construction would be awesome.
Even better, a 5 inch diaphragm driver development that goes 350hz to 16khz..... (the dream for me) Screw the cost, I would buy this. You can have bigger distances between drivers as hearing is less sensitive in the crossover range.
Building with carbon fiber in large quantity is cheaper than anything. Much cheaper than any metal for anywhere near comparable performance. To make a bike or (sailboat) mast that is light and strong out of metal you need precision machining or hydroforming. With CF, it's just a blow mold.
If you are building a one-off prototype in CF I agree that it can get expensive. But for volume production CF is really cheap.
Still, alu masts are a lot cheaper than a corresponding in carbon. But since when did production cost necessarily correspond to purchase price?
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Think about a carbon tennis racket. They are available at even super cheap price points. In fact carbon tennis rackets appear to have even displaced aluminum, which is kind of shocking to me as an aluminum tennis racket is no more than an extrusion bent around a form with a handle bonded to it. I guess that even such a simple manufacturing process is still more expensive than a molded carbon fiber sock.
As regards masts - the length might have something to do with it. It's pretty easy to make long tubes and somewhat harder to make long CF tubes. They are probably too long to mold and must be mandrel wound (or perhaps bonding a few smaller molded tubes).
Anyways, let's talk about speakers!
As regards masts - the length might have something to do with it. It's pretty easy to make long tubes and somewhat harder to make long CF tubes. They are probably too long to mold and must be mandrel wound (or perhaps bonding a few smaller molded tubes).
Anyways, let's talk about speakers!
